Lubricant



United States Patent 3,234;1s0 LUBRICANT James Nixon, Elizabeth, and Rudolph Kassinger, West- This invention relates to lubricants. Particularly, the

invention relates to lubricating oil compositions, having good antiwear properties, comprising mineral oil and alkaline earth metal salts of acetic acid and alkenyl succinic acid. While generally useful'as lubricants for a variety of purposes, lubricants can be made according to-the invention which are particularly-effective for lubrication of marine diesel engines. Although; marine diesel engines have become widespread in their use, inthese engines there has always been a serious wear'problem withregard to the piston, the piston rings and the-surface ofthe'cylinder liner.

In lubricating these diesel. engines, a fluid or semi-fluid lubricant is generally sprayed or forced'directly onto the cylinder and piston upon each stroke of the piston by means of a centralized force-feed lubrication system.

The lubricant is to a large extentrconsumed during each stroke of the piston, thereby'reqniring continuous application of the lubricant:

In order to be suitable for such lubrication use, the lubricant should have a fluid or semi-fluid consistency. This is desired in order thattlie lubricant may bereadily pumped through the aforementionedv forced lubrication systems normally associated with marine diesel engines and will spread or wet the piston suificiently during each stroke to achieve an overall coating on the piston surface. As indicated above, another. requirement. of such lubricants is that they have good antiwear properties. Because of' the giant size of the pistons and cylinders-used in such engines ('e.g., piston and cylinder diameters of 36 to 60 inches are common), wear is a serious problem. Once the cylinder liner has worn more than about 0.6% of its diameter, it is necessary that the replaced. Wear of the piston and rings is also an expensive problem. In a typical marine engineof 8 to 16 cylinders the replacement costs due to wear, may run in the order of several thousand. dollars per cylinder. Furthermore, the lubricant shouldbe stable, even when subjected to long periods of vibration as occurs during storage in a ships engine room and in the presence of minor amounts of moisture.

Lubricants for such marine diesel lubrication, which met the above requirements,, have been made by thickening mineral lubricating oil with mixed calcium salts of acetic acid and intermediatemolecula-r weight fatty acid, e.g., C to C fatty-acids. It has now been found that marine diesel lubricants superior in several respects to those made from acetic: and intermediate molecular weight fatty acids, can be prepared by using an alkenyl succinic acid or anhydride in place of part orall of the intermediate molecular weight fatty acid. By the use of the alkenyl succinic acid or anhydride, marine diesel lubricants can be prepared which are superior to-sai'd intermediate fatty acid type lubricant by having a reduced tendency to gel, particularly at high-temperatures. Thus, insorne engines operating at very high temperatures, gelling of the lubricant will interfere with the spreading of the lubricant onto the piston and cylinder, and will also interfere 3,234,130 Patented Feb. 8, 1966 ice with pumping the lubricant through narrow diameter feed lines. In addition, the. alkenyl. succinic anhydride results ina gooddispersion of. calcium acetate, excellent oxidation stability, etc.

Either alkenyl succinic anhydrides or the corresponding acids can be used. However, the anhydrides. are more readily. obtainable sincethey canbesimply preparedby reacting maleic anhydridewith an organic compound having a: double bond. at itsend to thereby give compounds of the general formula:

wherein R and-R. can behydrogen-or hydrocarbon radicais, either substituted (e.g., chlorinated or sulfurized) or unsubstituted, and can be aliphatic, acyclic, aromatic, etc., although at least one of said R and R must'be a hydrocarbon group. The total number of carbon atoms in R and R will generally be 40- to 250, and preferably will beSO'to Beca'useofits ready availability and low cost, the alkenyl.- portion of the molecule is preferably obtained by reacting a. polymer of. a C to C monoolefin with maleic anhydride, said polymer generally having a molecular'weight ofabout 700 to 3,000, e.g., about 800 to 1300.- A preferred'example-of such an olefin polymer is polyisobutylene.

The preparation of alkenyl succinic anhydride is known in the art, for example, see US; 3,018,250, col. 3, lines 57 to 71, Example 1. The process simply involves heating about equal molar: proportions. of maleic anhydride and the olefinic material together;

Thealkaline earth metal component of the mixed salt compositionis preferably calcium since it results in the production of stable lubricants having exceptionally good loadi carrying. and antiwear characteristics. The other alkaline earth metals such as barium, strontium and magnesium' can be used, but are not as good as calcium in these respects.

The mixtureof alkaline earth metal salts of the invention canbe prepared by neutralization of acetic acid or acetic-anhydride, and alkenyl succinic anhydride, or alkenyl succinic acid, with suitable alkaline earth metal bases, e.g., ime. The neutralization stcpcan be carried out'in situ in the oil menstruum to which the mixture of salts is to be applied in actual use followed by dehydration by heating, e.g-., by heating about250 to about 350 F. until the salt mixture is substantially anhydrous, i.e-., there is little or no free or unbound water present.

The mixture of alkaline earth metal salts of the invention can also be prepared by separately preforming the alkaline earth-metal alkenyl succinate, then forming the acetate salt in' situ in the oil by neutralization in the presence'o fsaid'alk'enyl succinate, then heating todehydrate the resulting composition. This method is believed to result in a more stable lubricant since thealready formed alkenyl succinate is believed to limit the crystal growth of the acetate salt particles which are subsequently-formed by the neutralization of the acetic acid (or acetic anhydride) with alkaline earth metal base. A preferred specific method using lime is as follows:

Alkaline earth metal base, e.g., lime, is dispersed in 'might have been formed by said adjustment.

lubricant.

Gaulin homogenizer, etc.

a portion of the oil to form a slurry. If alkenyl succinic anhydride is to be used, then preferably about one mole of water, per mole of alkenyl succinic anhydride to be subsequently added, is next added to the kettle and mixed with the oil-lime slurry. The water converts the alkenyl succinic anhydride into its acid form which is more reactive and more readily forms succinate than the anhydride. Alkenyl succinic anhydride is next added. The resulting mixture can then be heated until most of the water is driven off, for example, until 90 to 95 wt. percent of the total amount of water present has been evaporated in order that the total dispersancy power of the calciumsuccinate is available for dispersing the calcium acetate formed in a subsequent step of this process. The system is then preferably cooled below 150 F., and acetic acid or acetic anhydride is slowly added with stirring, preferably while keeping the temperature below 150 F. in order to minimize the volatilization of acetic acid (or 4 ing Examples I to IV-of the invention, was prepared as follows: 1200 poundsof polyisobutylene of, about 1100 molecular Weight (Staudinger), and 150 pounds of maleic anhydride were heated together at a temperature of about 450-460 F. for about 24hours. The reaction mixture was maintained in a N atmosphere during the course of the reaction. The heated mixture was then cooled to about 212 F. and filtered. The recovered reaction prodacetic anhydride) before it has reacted. The reaction a mixture is then heated to evaporate water resulting from the acetate formation, and the neutralization numberzof the reaction mixture is checked. The system is then adjusted, if necessary, by minor additions of acetic acid (or a lime-oil slurry), preferably to a free acidity'of about .1 to 5 wt. percent, based on the weight of the total composition, as free oleic acid. The mixture is then reheated again, if necessary, to complete the dehydration and to evaporate any additional water of reaction that While the final product can be basic, neutral or acidic, it is prefer.- ably acidic so as to insure'that all the lime has been completely reacted. Additional oil is thenadded by simple mixing to form the final product.

The mixed salt lubricants of the invention can be prepared by using 1 to 100, preferably 5 to 40, molar hydrogen equivalents of acetic acid or acetic anhydride per molar hydrogen equivalent of alkenyl succinic anhydride or alkenyl succinic acid. For lubricants designed for marine diesel lubrication, good results are obtained by using a ratio of about 7 to 25, e.g., 10 to 2O, molar hydrogen equivalents of the acetic acid or its anhydride.,per

ture, lubricant bases or concentrates of about '12 to wt. percent of the mixed salts in oil can be made by the in situ technique, after which the concentrate is diluted by simple mixing with additional oil to form the finished can be homogenized in a Morehouse mill, Charlotte mill, If enough of the mixed salt is used in the oil to form a concentrate, a soft solid grease is obtained. As a result, the mixed salt composition of the invention is preferably used in the form of fluid or semi-fluid lubricant.

Mineral oil is the preferred lubricating oil when the lubricant is designed for marine diesel use. Various synthetic oils such as polysilicone,silanes, esters, Ucons, etc. may beused to-make other specialty lubricants.-

Various additives can be added to the finished lubricant in amounts of 0.1 to 10.0 wt. percent, based on the weight of the finished lubricant. Among additives that can be added are corrosion inhibitors such as sodium nitrite,

lanolin, wool grease stearin; antioxidants such as phenylalphaenaphthylamineg extreme pressure agents; dyes; other salts and soaps as auxiliary thickeners or as 13.1. or antiwear agents; etc.

Both the concentrate and finished lubricant- 'ucts (III-B and IV-B) of Examples lll'and IV were prepared according to :the procedure .of Example I, Parts A 1 and B, but using difie'rent proportions of materials.

The invention will be further understood by i-eferembodiments of the invention. 7

Polyisobutenyl succinic anhydride, used in the follow- Tences to the following examples which include preferred a mixture acidic.

(All parts by weight) Part A.A concentrate (LA) was prepared as follows:

4.04 parts of hydrated lime was slurried together with about 84.1 parts of mineral lubricating oil of SUS viscosity at 210 F. Next, .2 parts of water was added to the mixture and stirred. E The mixture was warmed to 180 F. and then 6.26 parts .of=warm (180 F.) polyisobutenyl succinic anhydride was slowly added with stirring. The resulting mixture was then heated to 300 F. for

about one hour, which evaporated about wt. percent of the total amount'of water initially added. The reaction mixture was then cooled slightly below F. r 5.6

parts of glacial acetic acid was slowly added tothe re-' action mixture .with stirring while maintaining the temperature .of the, reaction mixture below. 150 F; The

reaction mixture was then heated while evaporatingwater to a maximum temperatureof about 250 F and the neutralization number was then checkedrand found to be about 0.5 wt. percent as NaOH;f A small amount of ad-, ditional acetic acid was then added to-make the reaction The mixture was then further heated to 320 F. and maintained at this temperature for about l hour in order to complete the reaction'and dehydrate the mixture of any unboundor free water. The resulting concentrate was then homogenized by passing through a Y M'orehouse mill: While the concentrate can be used as a lubricant per, se,:it is preferably diluted as illustrated in Pa'rtB Whichfollows:

Part B.The concentrate, prepared. above was mixed with additional mineral lubricating .oil. The resulting :diluted product was homogenized by passing through a Morehouse mi1l, followed by milling in a laboratory 3- i roll paint mill to form the final product I-B: The latter procedure of Example I, PartA except that different proportions ofingredients were used, and 0.82 part of phenyl ix-naphthylamine was added as anoxidation inhibitor.

This concentrate was then diluted and homogenized according to the procedure of Part B of Example I to form lubricant II-B.

Examples 111 and IV The concentrates. (lll A and IV.B) and dilutedprod- Comparison lubricant For comparison, a marine, diesel. cylinder lubricant was prepared byconeutralizing inoil, with lime, acetic acid andWecoline' AAC acid. Wecoline AAC acid .is a commercial acid ,derived from coconut oil and consisting of;

about 46 wt. percent capricfacid, about 28 wt. percent caprylicacid and about. 26wt. percent lauric acid. This The compositions .of the lubricant. concentrates, the

finished lubricants, and the properties of the finished lubricants are summarized in the following table:

(1) at normal room temperatures as demonstrated by only 0.5 vol. percent of sediment after 4 hours in a centri- TABLE Examples Comparison lubricant I-A I-B II-A II-B III-A III-B IV-A IV-B Composition (parts by wt):

Polyisobutenyl succinic anhydride 2. 1G 2. 09 0. 45 8. 65 2. 16 Glacial acetic acid 3. 86 18. 75 3. 99 15. 45 3. 86 3. 84 Hydrated lime 2. 64 12. 25 2. 60 10. 55 2. 64 2. 70 Wecoline AAO acid 0.93 Phenylanaphthylamine 0. 21 0 80 .20 0.2 Mineral lubricating oil (80 SUS/210" F.) 91.13 66. 91 92. 96 64. .55 91.14 92. 33 Mole H equivalent ratio, acetic/higher acid.-- 20/1 10/1 10/1 20/1 20/1 12/1 Properties:

Centrifuge solids, vol. percent after 4 hours 0.5 0.5 0.8 Sulfated ash 5. l1 5. 11 5. 15 Visc. at 100 F. (SSU 1,665 1, 787 Vise. at 210 F. (SSU)- 9 .0 8.8 4-Ball Wear Test: Scar diameter in mm. (1,800

r.p.m., 1 hour, 75 C., 10 kg. load) 3 Manzell Lubricator, days 18 Water sensitivity, centrifuge solids:

After addition of 0.1% water After addition of 0.2% water Neut. No. ASTM-DGM, mg. KOH/gm 29.6 Neut. N 0. as wt. percent oleic acid Thermal stability test:

at 150- o N0 e at 190 C Gel The Manzell Lubn'cator test was carried out by passing the lubricant under test through a Manzell Lubricator at the rate of 2 quarts of lubricant a day. The Manzell Lubricator includes a sight-glass filled with an aqueous solution containing 20 wt. percent of calcium nitrate tetrahydrate as the sight-glass fluid. These lubricators are widely used in conjunction with marine diesel engines. The lubricator permits visual observation of the rate of flow of the lubricant which is forced into the bottom of the sight-glass and then floats up through the higher density sight-glass fluid to an upper line from where it is then forced to the cylinder being lubricated. The product of Examples II-B and III-B Went for 44+ days without displacing the aqueous fluid in the sight-glass. On the other hand, the comparison lubricant Went for only 18 days before the sight-glass fluid had become sufficiently displaced so as to require disassembling and cleaning. Since there is usually a sight-glass for each cylinder of a marine diesel engine, it is highly desirable from a labor standpoint to clean the sight-glasses as seldom as possible.

The Thermal Stability test was carried out by filling an ASTM pour point jar full with the lubricant to be tested. The test lubricant is heated for four hours and is then allowed to cool for 45 minutes. The jar is then examined to see if the lubricant has gelled. It is seen that at the 190 C. heating level, the comparison lubricant had gelled, while none of the products of the invention had gelled. This gelling, or lack of gelling, is used as an indication of the spreading ability of the lubricant when it hits the hot cylinder it is being used to lubricate. For example, a cylinder at a temperature of 190 C., when hit by the comparison lubricant of Table I, would cause the lubricant to gel so as to interfere with the spreadability of the lubricant along the cylinder walls. On the other hand, the products of Examples I to IV will not form a gel at this temperature and as a result will remain fluid so that they can rapidly spread along the cylinder to more evenly Wet the cylinder with the lubricant and hence lubricate more effectively.

In addition, the products of the invention, i.e., IB, II-B, III-B, and IV-B, gave very low rates of wear as demonstrated by the wear scar diameters ranging from 0.216 to 0.233 mm. in the 4-Ball Wear Test as compared to a scar diameter of 0.3 for the comparison lubricant. Also, the products of the invention had good stability fuge, (2) when contaminated by small amounts of water and (3) at high temperatures, e.g., the C. Thermal Stability Test.

While the preceding has been primarily directed towards lubricants useful as marine diesel lubricants, the products of the invention can be used for other lubricating purposes.

What is claimed is:

1. A fluid lubricant useful for lubricating cylinders of marine diesel engines consisting. essentially of a major amount of mineral lubricating oil and about 5 to 12 wt. percent of calcium salts of acetic acid and alkenyl succinic acid containing within the range of 50 to 250 carbon atoms in said alkenyl group, wherein the molar hydrogen equivalent ratio of salt of acetic acid to salt of said alkenyl succinic acid is about 5:1 to 40: 1.

2. A fluid lubricant according to claim 1, wherein said alkenyl group is polyisobutenyl having a molecular weight of about 800 to 1300 and wherein said ratio is about 7:1 to 25:1.

3. A method for preparing a stable fluid lubricating composition useful for lubricating cylinders of marine diesel engines, comprising a major amount of mineral lubricating oil and about 5 to 12 wt. percent of calcium salt of acetic acid and alkenyl succinic acid in a molar hydrogen equivalent ratio of salt of said acetic acid to salt of said alkenyl succinic acid of about 5:1 to 40:1, wherein said alkenyl group contains within the range of 50 to 250 carbon atoms, which comprises forming a dispersion of calcium salt of said alkenyl succinic acid in at least a portion of said lubricating oil, then forming calcium salt of acetic acid by neutralizing acetic acid with lime in situ in said dispersion, heating to a temperature of about 250 to 350 F. to dehydrate the composition, and cooling.

References Cited by the Examiner UNITED STATES PATENTS 2,528,373 10/1950 Knowles et al. 25240.5 2,868,729 1/1959 Nelson et al 25239 2,980,615 4/1961 Morway et al 25241 3,076,763 2/1963 Nelson 252-39 DANIEL E. WYMAN, Primary Examiner. 

1. A FLUID LUBRICANT USEFUL FOR LUBRICATING CYLINDERS OF MARINE DIESEL ENGINES CONSISTING ESSENTIALLY OF A MAJOR AMOUNT OF MINERAL LUBRICATING OIL AND ABOUT 5 TO 12 WT. PERCENT OF CALCIUM SALTS OF ACETIC ACID AND ALKENYL SUCCINIC ACID CONTAINING WITHIN THE RANGE OF 50 TO 250 CARBON ATOMS IN SAID ALKENYL GROUP, WHEREIN THE MOLAR HYDROGEN EQUIVALENT RATIO OF SAID OF ACETIC ACID TO SALT OF SAID ALKENYL SUCCINIC ACID IS ABOUT 5:1 TO 40:1. 